Many times you will have an object in your drawing, like a viewport for instance, which you want to be visible for editing purposes but that you do not want to plot. A common way to accomplish this is to place the object on the Defpoints layer. AutoCAD automatically creates the Defpoints layer when dimensions are added to the drawing and it’s purpose is to contain the definition points at the end of the dimension lines. The Defpoints layer is designed not to plot and allows you to view and edit it’s contents. So it is natural that people place other objects on this layer that they want to be visible but they don’t want to plot. The problem is that AutoCAD will crash if you perform a REGEN while the Defpoints layer is frozen. So the best option is to leave the Defpoints layer alone. Let AutoCAD use it for what it needs it for and ignore it.
If you want to have objects on a viewable layer that won’t plot you can create your own layer that will do just that. In our example of the viewport what I usually do is create a layer called Viewports. Then in the Layer Dialog box activate the Do Not Plot option.
You have just created a layer that is visible and will not plot. And it won’t cause any problems if you freeze it.